Hitherto, high dynamic range imaging (HDR) has been realized by various methods based on a plurality of images taken of the same subject.
These technologies are described in Patent Documents 1 to 3, for example.
In the method described in Patent Document 1, a plurality of input images having different exposure amounts are received, and a luminance value region in a set luminance range in each image is extracted to generate an HDR image using the region. Moreover, in the method described in the document, a plurality of luminance range set values are used to extract luminance value regions having the set values from each image and generate a large number of HDR images, and the HDR images are combined with a standard image to synthesize an HDR image to be finally output.
Also in the methods described in Patent Documents 2 and 3, processing operation is performed so that a plurality of input images are received, and a desired region is extracted from each input image to fill a too bright region and a too dark region in a standard image. In the method in Patent Document 2, a plurality of input images taken under the same image pickup conditions are acquired, and the input images are superimposed on each other by subjecting luminances in the same pixel portion to addition processing to obtain an HDR image. Moreover, in the method in Patent Document 3, an image pickup unit having a special structure is used to acquire a plurality of input images taken under different exposure conditions, each image is normalized and evaluated for reliability, and the images are synthesized in accordance with the reliability to obtain an HDR image.
In Non Patent Document 1, a Poisson synthesis method, which may be adopted in embodiments to be described below, is described.